<template>
  <div class="s-canvas" @click="Refresh" style="cursor:pointer">
    <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>
<script>
  export default {
    name: "SIdentify",
    props: {
      identifyCode: {
        // 默认注册码
        type: String,
        default: "1234",
      },
      fontSizeMin: {
        // 字体最小值
        type: Number,
        default: 25,
      },
      fontSizeMax: {
        // 字体最大值
        type: Number,
        default: 35,
      },
      backgroundColorMin: {
        // 验证码图片背景色最小值
        type: Number,
        default: 200,
      },
      backgroundColorMax: {
        // 验证码图片背景色最大值
        type: Number,
        default: 220,
      },
      dotColorMin: {
        // 背景干扰点最小值
        type: Number,
        default: 60,
      },
      dotColorMax: {
        // 背景干扰点最大值
        type: Number,
        default: 120,
      },
      contentWidth: {
        // 容器宽度
        type: Number,
        default: 90,
      },
      contentHeight: {
        // 容器高度
        type: Number,
        default: 38,
      },
    },
    methods: {
      Refresh() {
        this.$emit("Refresh")
      },
      // 生成一个随机数
      randomNum(min, max) {
        return Math.floor(Math.random() * (max - min) + min);
      },

      // 生成一个随机的颜色
      randomColor(min, max) {
        let r = this.randomNum(min, max);
        let g = this.randomNum(min, max);
        let b = this.randomNum(min, max);
        return "rgb(" + r + "," + g + "," + b + ")";
      },
      //画图
      drawPic() {
        let canvas = document.getElementById("s-canvas");
        //创建一个2D对象作为上下文。
        let ctx = canvas.getContext("2d");
        ctx.textBaseline = "bottom";
        // 绘制背景
        ctx.fillStyle = "#e6ecfd";
        ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
        // 绘制文字
        for (let i = 0; i < this.identifyCode.length; i++) {
          this.drawText(ctx, this.identifyCode[i], i);
        }
        this.drawLine(ctx);
        this.drawDot(ctx);
      },
      //在画布上显示数据
      drawText(ctx, txt, i) {
        ctx.fillStyle = this.randomColor(50, 160); // 随机生成字体颜色
        ctx.font =
          this.randomNum(this.fontSizeMin, this.fontSizeMax) + "px SimHei"; // 随机生成字体大小
        let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
        let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
        var deg = this.randomNum(-30, 30);
        // 修改坐标原点和旋转角度
        ctx.translate(x, y);
        ctx.rotate((deg * Math.PI) / 180);
        ctx.fillText(txt, 0, 0);
        // 恢复坐标原点和旋转角度
        ctx.rotate((-deg * Math.PI) / 180);
        ctx.translate(-x, -y);
      },

      // 绘制干扰线
      drawLine(ctx) {
        for (let i = 0; i < 4; i++) {
          ctx.strokeStyle = this.randomColor(100, 200);
          ctx.beginPath();
          ctx.moveTo(
            this.randomNum(0, this.contentWidth),
            this.randomNum(0, this.contentHeight)
          );
          ctx.lineTo(
            this.randomNum(0, this.contentWidth),
            this.randomNum(0, this.contentHeight)
          );
          ctx.stroke();
        }
      },

      // 绘制干扰点
      drawDot(ctx) {
        for (let i = 0; i < 30; i++) {
          ctx.fillStyle = this.randomColor(0, 255);
          ctx.beginPath();
          ctx.arc(
            this.randomNum(0, this.contentWidth),
            this.randomNum(0, this.contentHeight),
            1,
            0,
            2 * Math.PI
          );
          ctx.fill();
        }
      },
    },
    watch: {
      identifyCode() {
        this.drawPic();
      },
    },
    mounted() {
      this.drawPic();
    },
  };
</script>